Dielectric constants of liquid formamide, N-methylformamide and dimethylformamide via molecular Ornstein-Zernike theory

Richardi, Johannes; Krienke, Hartmut; Fries, Pascal

doi:10.1016/s0009-2614(97)00588-5

Cited by 60 publications

(41 citation statements)

References 19 publications

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“…In a recent MOZ study of an OPLS model for formamide 40 the internal excess energy was also 15% too small with respect to the simulations, whereas the dielectric constants were in excellent agreement. This agreement may be due to the special features of the liquid structure in formamide and shows that the results obtained here cannot be generalized to all protic solvents.…”

Section: Comparison Of Thermodynamic Propertiesmentioning

confidence: 81%

A molecular Ornstein–Zernike study of popular models for water and methanol

Richardi

Millot

Fries

1999

The Journal of Chemical Physics

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Some effective models of water ͑TIP3P, SPC, SPC/E, TIP4P͒ and methanol ͑OPLS, H1͒ are studied with the help of the molecular Ornstein-Zernike ͑MOZ͒ theory using the hypernetted chain ͑HNC͒ approximation. The quality of the results obtained within the HNC approximation is discussed by comparison with values from molecular dynamics ͑MD͒ simulations. The MOZ-HNC theory yields internal excess energies and dielectric constants which are about 20% smaller than the simulation results found in the literature. The relative trends of the properties observed by simulation for the different interaction models are correctly predicted. In order to calculate the rotational invariant coefficients which define the liquid structure, new MD simulations were carried out. The rotational invariant coefficients derived from the simulation and from the MOZ theory strongly differ. In particular, the center-center distribution functions show that the theory is not able to reproduce the tetrahedral structure of water. In this solvent a comparison of the O-H distribution function indicates that the MOZ theory underestimates the H bonding. The use of a spherically symmetric bridge function in the reference HNC approximation does not lead to an improvement of the MOZ results. The observed defects of the MOZ-HNC approach contrast with the good agreement found for aprotic solvents and are presumably due to the association by H bonds in water and methanol.

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Section: Comparison Of Thermodynamic Propertiesmentioning

confidence: 81%

A molecular Ornstein–Zernike study of popular models for water and methanol

Richardi

Millot

Fries

1999

The Journal of Chemical Physics

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“…As above indicated for the case of the 1d ‐FM system, a cosolvent might be required because of the insolubility of 1d in FM, but this rationale does not apply to the similar 1d ‐NMF system. The need of a cosolvent might be related to the reported disruption of the H‐bond structure of the amide caused by its presence;29 or with an efficient solvation of the product by the cosolvent. Further work is needed to clarify this phenomenon.…”

Section: Resultsmentioning

confidence: 99%

Radical anions containing the dioxidated 1,2,5‐thiadiazole heterocycle. Part II

Mirífico

Caram

Gennaro

et al. 2010

J of Physical Organic Chem

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Radical anions from several 3,4-aryl-disubstituted derivatives of 1,2,5-thiadiazole 1,1-dioxide were accumulated through chemical reduction of the substrates in aprotic solvents. The radical anions were characterized by electron spin resonance and cyclic voltammetry. DFT theoretical calculations were also performed for the 3,4-diphenyl derivative. The course of the reductions was followed using cyclic voltammetry. Uncommon reductants, such as amides, were found to be effective under certain conditions.

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“…The estimation of the dielectric constant in the remaining proteins was based on recent studies, which infer that the value of ε in the core of a protein is higher than usually considered (Schaefer et al 1997; Garcia‐Moreno et al 1997). The protein interior should be rich in strong dipoles, as N‐methylformamide, which is taken as the solvent analog of the peptide groups and has a very high dielectric constant, ε = 186 (Richardi et al 1997). The calculated dielectric constant can be very low if only electronic polarization is taken into account, while quite different are the values when the nuclear motions are accounted for.…”

Section: Discussionmentioning

confidence: 99%

On the involvement of electron transfer reactions in the fluorescence decay kinetics heterogeneity of proteins

Ababou

Bombarda

2001

Protein Science

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Time-resolved fluorescence study of single tryptophan-containing proteins, nuclease, ribonuclease T1, protein G, glucagon, and mastoparan, has been carried out. Three different methods were used for the analysis of fluorescence decays: the iterative reconvolution method, as reviewed and developed in our laboratory, the maximum entropy method, and the recent method that we called "energy transfer" method. All the proteins show heterogeneous fluorescence kinetics (multiexponential decay). The origin of this heterogeneity is interpreted in terms of current theories of electron transfer process, which treat the electron transfer process as a radiationless transition. The theoretical electron transfer rate was calculated assuming the peptide bond carbonyl as the acceptor site. The good agreement between experimental and theoretical electron-transfer rates leads us to suggest that the electron-transfer process is the principal quenching mechanism of Trp fluorescence in proteins, resulting in heterogeneous fluorescence kinetics. Furthermore, the origin of apparent homogeneous fluorescence kinetics (monoexponential decay) in some proteins also can be explained on the basis of electron-transfer mechanism.

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Dielectric constants of liquid formamide, N-methylformamide and dimethylformamide via molecular Ornstein-Zernike theory

Cited by 60 publications

References 19 publications

A molecular Ornstein–Zernike study of popular models for water and methanol

A molecular Ornstein–Zernike study of popular models for water and methanol

Radical anions containing the dioxidated 1,2,5‐thiadiazole heterocycle. Part II

On the involvement of electron transfer reactions in the fluorescence decay kinetics heterogeneity of proteins

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